Glass-drawing process and apparatus.



L. THORNBURG.

GLASS DRAWING PROCESS AND APPARATUS.

APPLKGATION FILED SEPT. 3, 1908.

Patented 1060.27, 1910.

2 SHEETS-SHEET1I WITNESSES L. A. THORNBURG.

GLASS DRAWING PROCESS AND APPARATUS.

APPLICATION FILED SEPT.3,1908.

?Q 6@l B Patented Dec. 27, 1910.

2 SHEETB-SHEET 2.

INVENTOR,

WiTNESSES uni;

PATENT tlh ld ltjl LINCOLN A. THORNBURG, OT. MUNGIE, INBIANA. ASSIGNOR OF ONE-i-iALF TC AMERI- CAN 'WENDOW GLASS EORATIGN OF NEW JERSEY.

MACHINE CQMPANY, OE PI'ZTSBURG, PENNSYLVANIA, A GOR- GLASS-DBAW'ING PROCESS AND APPARATUS.

eraser.

Specification of Letters Patent. ntegrated than. 2?, 191%}.

3plieation filed September 3, 1908. Serial No. 451,474.

ratus, of which the following is a specificanon.

My invention relates to the art of drawing hollow glass articles such as the cylinders used for making window glass, particularly to the method ofdrawing from a large body of molten glass, and to the construction of furnaces, etc. for handling the glass for this purpose.

The primary object is to sinuiltaneou-sly attain the various advantages of drawing from a shallow depth, and the advantage of maintaining and melting back in a deep and large volume of glass.

'Other objects are to provide improved methods of clearing a drawing vessel of the residue glass left after severing the cylinder; to improve the construction of furnaces and drawing devices and to gain othenadvantages to hereinafter appear.

I have illustrated the invention in the accorppanying drawings, wherein- Figure lie a partial horizontal section of a melting; tank and plan view of one of my improved forehearths or so-called .doghouses. the forehearth, and partial sectionof the main furnace. Fig. 3 is a vertical section. taken on line lllf, Ill, in Fig. i. Fig 4 is a. broken verti'al section taken on line IV, IV, on Fig. 1. Fig. 5 is a section taken on line 5 in Figs. 1,.3, and 4'. Fig. 5 shows a modified form of the false bottom for the drawing rin Experience has shown it to be very diliicult to successfully draw a cylinder from a body of glass having any considerable depth, partly because the consistency of the metal cannot be controlled on account of convection currents, radiation from bottom, and other obscure causes which prevent. successful production. On the other hand great difficulty is met with when drawing from a shallow pot of glass in ll'lOlflUfI back the residue, and from improper cooling, etc. Successful and rapid melting back requires a deep body of glass. In m rcess the Fig. 2 is a left side elevation ofcylinder is drawn from whatis virtually a shallow body formed by using a floating ring which has a false bottom n'nmersed in p a large body of glass while the melting back is ellected in a deep body of glass at higher temperature.

Thus in the accompanying drawings I have shownfor illustration part of a large melting tanli 6, provided with one or more semi-circular forchearths 7 communicating with the main tank by two large openings. This forehearth is preferably heated not only by the radiation but also by tines 8 and 9, containing blow pipes 10, as shown in Fig. 4, the gases being carried out by a down-take flue 11. shown in Fig. 1. As seen rs iiecially in Figs. i and 5. there pla :ed

in the inlet opening 12 to the forehcarth a refractory tile or block 13, con'ipletely submerged in the body of glass and located so that it is comparatively near the surface of the glass, and slants downward back from the mouth of the tank. The passage is enlarged about its center. The body of molten glass in the forehearth is continuous around the central partition 14 and COH1- niunicates again by the outlet 15 with the main body of glass in the tank. The partition 14: is provided with an ()POl'llllg 10 clear through to the cellar, so that by circulation of air the ten'ipcrature conditions on both.

sides of the body of glass surrounding the plate, drawing point and tile 13 may be the same, and this tile may be hollow when desired to better control its temperature, the passage 13 being: covered by a damper 13" whose handle 13 can be adjusted by spring catch 13 The inlcadingr passage from 12, enlarged as shown at 17 in Fig. 1, forms a drawing chamber above the false bottom block 13. In conjunction with this false drawing bottom I use a series of floating rings 18, i8. 18, etc... which are of such depth as to almost reach the block 13 when the rings are in the position in chamber 17 as shown in Fig. t. It will be seen that by reasonof the slope of block 13 the quair lily of glass beneath the drawing ring is deeper on the inner side where the glass is apt to beof lower temperature. Covering the drawing chamber is a so-called top stone 19, which as shown in Figs. '1 and 5 I prefer to mount on bars 20 pivoted on hinges 21,

and operated to open and close by the piston rod 22 of a cylinder 23. I also provide a refractory gate 24 which may, by means of a link 25, be also operated from the cylinder by the bars 20 supporting the top stone, so that the raising and lowering of the top stone will simultaneously and autonratically raise and lower also the gate 2 at the proper time, to shut off the radiation from the tank while drawing. I

The drawing rings to are preferably beveled to fit in, and be centered by, the top stone 19. \Vhen the parts are in the position shown in Figs. 4 and 5, the blow-pipe or bait 26 is lowered through the top stone and into the ring 18, and a cylinder tlr, is drawn upwardly by the carriage 27 and supplied with air as by the pipe 528, in the well known manner of the Lubbers process.

After the cylinder of sullicient length it will be understood that the glass is cut off at the bottom and of course a cold resi due of falls into the ring 18. The top stone 19 is now raised, and incidentally any waste glass or dirtleft on itis at once and automatically, dumped down the shaft 16. The ring 18 is now pushed backward into the main body of the fort-hearth arrying the cold glass and skimming the surface, back into the reducing chamber formed in the round part of the forehearth, and being heated not only by the large mass of glass communicatingdirectly with the tank, but also by the lines 8 and t). The ring containing the residue glass, being thusin a deep body of molten glass of the same temperature as the tank is rapidly and efficiently reduced or cleared, before the ring is eventually pushed out'into the tank again by the other rings which follow. Meanwhile the gate 24 being open another one of the rings 18 is pushed into the d rawlng chamber and over the false bottom t8, bringing in fresh glass from the tank, and thus the process is continued indefinitely.

In case one of the rings l8 becomes broken or is too difficult of clearing. it may be drawn out and dumped down the large intake fiue9; this has a small opening 29 for insertion of a tool. The temperature of the glass in the reducing chamber of the forchearth is preferably kept the same as that in the melting tank, while the drawing point is kept cooler on account of the shallow body, and may be controlled by the air passage 13. It will thus be seen that the glass cylinder is drawn from a body of glass which, so far as effects on the drawing are concerned. is shallow and controllable, and yet which by reason of free communication with a large body of glass and by reason of the false bottom 13 being submerged in the large body of glass, is not subject to variations and is as deep as in the big tank. so as not. only to keep temperature conditions constant and residue immediately in a large body of glass without ever lifting out the receptacle, will readily occur to those familiar with the art; and the construction of the furnace described makes the operation easy, efficient and very uniform and certain.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is the following:

l. The method of forming glass articles which comprises drawing them upwardly from a bath of molten glass and meanwhile controlling thetemperature of the glass at a level intermediate betweentlie drawing point and the bottom of the mass of glass.

2. The method of forming glass articles which consists in drawing them upwardly from a bath of molten glass and controlling the flow and temperature of the glass at a level intermediate between the drawing pointand the bottom of the mass of molten glass.

3. The process of drawing glass articles which comprises drawing the upwardly from a bath of large volume, controlling the flow of glass to the drawing point by an open ring around the same, and controlling the temperature of the glass at a point below the drawing ring but abovethe bottom of the bath.

l. 111 the art of drawing glass articles, the method of controlling the flow and temperature of the glass near the drawing point. by drawing it under an open ring and over a submerged cooling block placed between the ring and the bottom of thebath, substantially as described.

I n the art of drawing glass cylinders,

the by means of a submerged plate above the bottom of the bath.

(5; In the art of drawing glass articles, the step in the process which comprises successively passing a series of floating rings over a submerged temperature controlling plate, drawing the article from within the ring while it isover'the plate, and floating the ring to a ditlerent part of thebath for melting out the. residue while another article is being drawn from another ring.

7. Apparatus for drawing glass articles comprising thecombination of a floating ring in the glass .bath and a submerged false bottom plate under and separated from the ring but placed above the bottom of the bath, substantially as described.

8. The combination with a glass, melting tanlgof a floatii'ig ring therein and means to locally control the currents and temperature beneath the ring While drawing therefrom, and means to successively pass a series of such rings first over and then away from said controlling means.

9. The combination with a glass melting tank having a by-pass connected at both ends to the main body, aFsmall submerged plate at one end of said passage near the surface and a series of rings adapted to float over the plate and through the passage back to the main body of glass.

10. A melting furnace having a curved bypass channel, an enlarged drawing chamber in the channel provided *ith a submerged plate therein, and a deep reducing chamber beyond the plate.

11. The combination of a glass working furnace provided with a covered by-pass channel, a submerged plate near the surface of the glass therein atone end, a series of floating rings adapted to pass over said plate, and a deep chamber in the channel for remelting and clearing the rings after drawmg.

12A glass working furnace having a semi-circular forehearth with two openings to the main body of glass, a drawing ehanr her therein near one opening and a hollow partition wall between said openings.

13. The combination of a furnace having a forehearth with a drawing chamber therein provided with a false bottom and a deeper reducing chamber, of a series of floating rings adapted to pass over the false bottom, and a gate to close the opening to the furnace above-the false bottom.

14. The combination with a furnace forehearth, of a drawing chamber, a pivoted top stone thereon, a stop gate for the opening to the furnace, and a power cylinder arranged to simultaneously operate the top stone and gate.

15. A furnace foreliearth having a curved channel connected at both ends to the n in furnace body. a d "awing chamber in the channel, a hollow wall between said channel ends and a pivoted top stone mounted on the said wall.

16. A furnace having a semicircular forehearth having a continuous channel communicating with the furnace a drawing chamber therein provided with a false bottom and means to cool the sides and false bottom of said chamber.

17. In a glass drawing combination with a melting 1 drawing openingtherein, of a table or shieldlocated beneath the drawing opening above apparatus, the tank having a the bottom of the tank and below the level of the molten glass.

18. In glass drawing apparatus, the combination with a melting tank having a drawing opening therein, of a table or shield made of refractory material, located Within the tank below said drawing opening'and above the bottom of the tank and means for holding said table sulnnerged.

19. In glass drawing apparatus, the combination with a melting tank having a drawing opening therein, of a table or shield located within the tank in a plane below the working level of the melted glass and above the bottom of the tank whereby the melted glass may have free movement over the table, I shield or bench.

I In testimony whereof I have hereunto signed my name in the presence of the two subscribed witnesses.

hi LINCOLN A. Xi'FHORNBURG.

Witnesses F. WV. H. CLAY,

CLARA E. Tnoimninio. 

